Re: [PATCH 3/3] KVM: s390: pv: Allow AP-instructions for pv guests

Claudio Imbrenda
2023-07-27T15:08:16Z

On Thu, 27 Jul 2023 14:20:53 +0200
Steffen Eiden <seiden@linux.ibm.com> wrote:

> Introduces new feature bits and enablement flags for AP and AP IRQ
> support.
>
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
> ---
> arch/s390/include/asm/uv.h | 12 +++++++++++-
> arch/s390/kvm/pv.c | 8 ++++++--
> 2 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
> index 338845402324..913ccfaa9d76 100644
> --- a/arch/s390/include/asm/uv.h
> +++ b/arch/s390/include/asm/uv.h
> @@ -99,6 +99,8 @@ enum uv_cmds_inst {
> enum uv_feat_ind {
> BIT_UV_FEAT_MISC = 0,
> BIT_UV_FEAT_AIV = 1,
> + BIT_UV_FEAT_AP = 4,
> + BIT_UV_FEAT_AP_INTR = 5,
> };
>
> struct uv_cb_header {
> @@ -159,7 +161,15 @@ struct uv_cb_cgc {
> u64 guest_handle;
> u64 conf_base_stor_origin;
> u64 conf_virt_stor_origin;
> - u64 reserved30;
> + u8 reserved30[6];
> + union {
> + struct {
> + u16 reserved : 14;
> + u16 ap_instr_intr : 1;
> + u16 ap_allow_instr : 1;
> + };
> + u16 raw;
> + } flags;
> u64 guest_stor_origin;
> u64 guest_stor_len;
> u64 guest_sca;
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index 899f3b8ac011..103add1894c9 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -561,12 +561,16 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
> uvcb.conf_base_stor_origin =
> virt_to_phys((void *)kvm->arch.pv.stor_base);
> uvcb.conf_virt_stor_origin = (u64)kvm->arch.pv.stor_var;
> + uvcb.flags.ap_allow_instr = uv_has_feature(BIT_UV_FEAT_AP) &&
> + kvm->arch.model.uv_feat_guest.ap;

how can it happen that uv_feat_guest.ap is set but
uv_has_feature(BIT_UV_FEAT_AP) is 0 ?

in the previous patch you check for the feature before allowing the bit
to be set.

> + uvcb.flags.ap_instr_intr = uv_has_feature(BIT_UV_FEAT_AP_INTR) &&
> + kvm->arch.model.uv_feat_guest.ap_intr;

same here

>
> cc = uv_call_sched(0, (u64)&uvcb);
> *rc = uvcb.header.rc;
> *rrc = uvcb.header.rrc;
> - KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x",
> - uvcb.guest_handle, uvcb.guest_stor_len, *rc, *rrc);
> + KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x flags %04x",
> + uvcb.guest_handle, uvcb.guest_stor_len, *rc, *rrc, uvcb.flags.raw);
>
> /* Outputs */
> kvm->arch.pv.handle = uvcb.guest_handle;